1. oxidative decomposition: plants have been buried underground for a long time and are affected by oxidative decomposition. This will lead to the gradual decomposition and decay of organic and inorganic substances in the outer layer of cockroaches, forming tiny particles and powders.

2. Soil particles: cockroaches are buried underground, and there are tiny particles and powders in the surrounding soil. When dragonflies are dug up, these particles may adhere to the surface of dragonflies to form powder.

3. Physical function: In the process of digging and treating calluses, tools or machinery can be used to clean, shape or polish calluses. These physical actions may produce powder.